Gemmer Engine

Gemmer (formerly you-js) is a lightweight, modern 2D game engine built with JavaScript, Vite, and Electron. It features a robust Entity-Component-System (ECS) architecture designed for simplicity and ease of use.

Features

• ECS Architecture: Flexible Entity, Component, and System structure.
• Rendering: Canvas-based SpriteRenderer with support for anchors, pivots, and layers.
• Animation: Frame-based Animator system.
• Physics: AABB collision detection via BoxCollider.
• Input: Unified InputManager for Keyboard and Mouse.
• Audio: AudioManager for background music and sound effects.
• Cross-Platform: Builds for Web and Desktop (via Electron).

Getting Started

Installation

npm install gemmer

(Note: Currently in local development. Clone the repository to use.)

Quick Start

1. Initialize the Game:

import { Game } from 'gemmer';

const game = new Game({
    width: 800,
    height: 600,
    backgroundColor: '#333',
});

game.start();

2. Create an Entity:

import { Entity, SpriteRenderer, Sprite, Vector2 } from 'gemmer';

// Create a player entity
const player = new Entity('Player');
player.position = new Vector2(400, 300);

// Add a sprite
const sprite = new Sprite('assets/player.png');
player.addComponent(new SpriteRenderer(sprite));

// Add to game
game.addEntity(player);

3. Create a Custom Component:

import { Component, input } from 'gemmer';

class PlayerController extends Component {
    update(dt) {
        const speed = 200;

        if (input.isKeyDown('ArrowRight')) {
            this.entity.x += speed * dt;
        }
        if (input.isKeyDown('ArrowLeft')) {
            this.entity.x -= speed * dt;
        }
    }
}

player.addComponent(new PlayerController());

Architecture Overview

Core

• Game: The central hub that manages the game loop, scenes (entities), and systems.
• Entity: A general-purpose object in the game world. Has a Transform (position, rotation, scale) by default.
• Component: Data or logic attached to an Entity (e.g., SpriteRenderer, BoxCollider).

Systems

• InputManager (input): Handles user input.
  • input.isKeyDown(key)
  • input.mouse (Vector2)
• AudioManager (audio): Handles sound.
  • audio.play('bgm')
  • audio.playOneShot('sfx')

Development

Scripts

• npm run dev: Start the Vite development server.
• npm run dev-test: Launch the browser test suite.
• npm run electron: Launch the Electron desktop app.
• npm run test: Run headless unit tests.
• npm run build:lib: Build the engine library for distribution (npm).
• npm run dist: Build and package the game as a desktop application (.exe, .dmg).

License

MIT